The present invention relates generally to welding-type devices and, more particularly, to an inductor assembly having a molded bobbin so as to maintain a uniform gap between a pair of ferrite cores.
Inductor assemblies are commonly used with welding-type devices to condition a power signal from a power supply so that it may be used in the welding process. For example, inductor assemblies are often implemented in a boost converter assembly. Boost converters are frequently used so that the welding device may be operated on a variable voltage source. That is, the boost converter enables the welding device to be operable with voltages ranging typically from 115 volts to 230 volts. Typically, the signal is input to a rectifier that in turn outputs the rectified power signal to the boost converter for conditioning whereupon the boost converter outputs a conditioned signal to the inverter of the welding device and creates AC power for welding transformers of the welding device.
Typically, the boost converter or inductor assembly includes a pair of ferrite cores and several turns of magnetic wire that are collectively supported by a bobbin. Generally, shims are used to maintain a sufficient and constant gap between the two ferrite cores. Clips, typically fabricated from stainless steel, are then used to secure the ferrite cores to the bobbin. Customarily, the stainless steel clips are oriented to be parallel to the length of the cores. As a result, the clips “snap” onto protrusions on extreme ends of the bobbin. This configuration coupled with the bobbin being formed of notch-sensitive and extremely brittle material often results in bobbin breakage during the winding process where the winding stresses are typically very high.
Standard E-core inductors require shims or a ground center leg to formulate the necessary gap between the cores. These standard assemblies typically utilize a cylindrical sleeve designed to receive, at each end, the inner pole of an E-core such that the outer legs or pole of the E-cores are positioned outside the sleeve. As such, shims are used to maintain a gap between the facing outer poles. These shims increase the size and weight of the inductor assembly, but also lead to increased tooling and manufacturing costs. In other assemblies or in conjunction with the outer shims, the center pole is ground to a shorter length than the outer pole so that the gap between the inner poles is greater than the outer poles. This requires additional grinding of the core which yields greater tooling and manufacturing costs.
Adding to the complexity of these inductor assemblies is the mounting means by which the inductor assembly is secured within the boost converter. Typically, the mounting means for the inductor assembly is built into the brackets or clips used to hold the cores tight against one another. As a result, the bobbin is secondarily secured to a mounting plate.
It would therefore be desirable to design an inductor assembly having a bobbin that maintains the requisite distance between a pair of ferrite cores absent additional gap shims. It is also desirable to configure the bobbin so as to be directly mountable to a mounting plate. It would also be desirable to configure the bobbin to receive a pair of securing devices designed to secure the E-cores to the bobbin with reduced likelihood of bobbin breakage.